1. Field of the Invention
The present invention generally relates to a device and method for providing an additional service in a wireless terminal, and more particularly to an apparatus and method that can receive and process a digital broadcasting signal.
2. Description of the Related Art
Standardization for the current digital broadcasting is actively in progress in the world. For the digital broadcasting, a Digital Multimedia Broadcasting (DMB) system of the United States and a Digital Video Broadcasting (DVB) system of Europe are present. A wireless terminal having a digital broadcasting receiver is provided with a tuner, a demodulator, and a multimedia processor for digital broadcasting reception, and so on.
FIG. 1 is a block diagram illustrating an operation for multiplexing a Transport Stream (TS) signal in a digital broadcasting transmitter.
Referring to FIG. 1, a video encoder 111 of the transmitter encodes video data to generate a video Elementary Stream (ES). Here, the video ES may be video data based on Moving Picture Experts Group (MPEG)-2, MPEG-4, or H.264 standard. An audio encoder 121 encodes audio data to generate an audio ES. The audio ES may be audio data based on MPEG-1 (mp1/mp2/mp3), Advanced Audio Coding (AAC), or Bit Sliced Arithmetic Coding (BSAC).
A packetization process is required to multiplex video, audio, and data. Accordingly, a video packet assembler 113 adds time information, adaptation information and a packet header to a video ES signal and outputs a video Packetized Elementary Stream (PES). An audio packet assembler 123 adds the above-described information to an audio ES to be assembled in an audio packet, and outputs an audio PES signal. A data packet assembler (not illustrated) performs an operation similar as described above.
Then, a multiplexer 130 multiplexes video, audio, and data PES signals and outputs a TS signal. The multiplexer 130 performs a function for multiplexing a plurality of inputs into one output. Here, the inputs may be broadcasting information data packets associated with video, audio, programs, services, and so on.
In the structure of FIG. 1, the packet assemblers 113 and 123 and the multiplexer 130 may configure a TS multiplexer.
A demultiplexer 140 of the digital broadcasting receiver for receiving the multiplexed TS signal as described above has a structure as illustrated in FIG. 2.
Referring to FIG. 2, the demultiplexer 140 for receiving the TS signal analyzes header information of the TS signal, separates video, audio, and data, and outputs PES signals mapped thereto. A video packet disassembler 151 receives a video PES signal separated in the demultiplexer 140, analyzes a header of the received video PES signal, generates a video ES signal, and outputs the generated video ES signal to a video decoder 153. Similarly, an audio packet disassembler 161 and an audio decoder 163 perform the same operation as described above. In the following description, it is assumed that a demultiplexer includes the demultiplexer 140 and the packet disassemblers 151 and 161.
It can be seen that the demultiplexer of the digital broadcasting receiver performs the inverse operation of the multiplexer of the digital broadcasting transmitter. FIG. 3 is a block diagram illustrating a structure of the demultiplexer.
Referring to FIG. 3, a sync detector 211 detects a sync byte of a packet header from a received TS signal, and stores the received TS signal in an input buffer 221 when the sync byte is detected. The input buffer 221 buffers data of a packet size. A packet header processor 224 extracts and processes the packet header from the buffer 221 and outputs the remaining data except the packet header to a buffer 223. An adaptation information processor 215 extracts and processes adaptation information, and outputs the remaining data except the adaptation information to a buffer 225. A PES header processor 217 extracts and processes a PES header from the buffer 225, and outputs the remaining information except the PES header to a buffer 227. A data processor 219 extracts data from the buffer 227 and outputs a video or audio ES.
The conventional demultiplexer 140 with the structure as illustrated in FIG. 3 has a serial data processing structure. That is, when the sync detector 211 detects a byte sync signal, the input buffer 221 buffers subsequent data in a packet size. After data of one packet is buffered in the buffer 221, the packet header processor 224 operates and analyzes a packet header. The conventional demultiplexer as described above is provided with the buffers 221 and 223 in front-ends of the processors, and employs a method for receiving processed packet data from the front-ends to process packets. Because the demultiplexing operation is performed in the serial structure, delay occurs when the input TS signal is multiplexed.
The above-described serial demultiplexing structure may unnecessarily perform a data processing operation. In this case, the packets configuring the input TS signal may not include adaptation information and/or PES information. That is, the packets configuring the received TS signal may be mostly constructed by true data. In this case, the packets constructed by only the true data also pass through the adaptation information processor 215 and/or the PES header processor 217. An unnecessary processing operation is performed which may increase system load and reduce a processing rate. Actual data packets (or audio/video data ESs) of the input packet data are mostly present in PES header packets. Accordingly, the PES header processor mostly transfers data to the data processor such that an ES can be extracted.
The structure of the demultiplexer as illustrated in FIG. 3 is provided with the buffers 221 to 227 in the front-ends and/or rear-ends of the processors. In this case, a buffer memory increases because the buffers 221 to 227 have the capacity of more than a packet size.
FIG. 4 is a flowchart illustrating a procedure for detecting synchronization of a TS signal (or packet stream) input to the demultiplexer.
Referring to FIGS. 3 and 4, the sync detector 211, checks bytes of the input TS signal. If an input byte is a sync byte of “0X47”, the sync detector 211 detects the sync byte in step 461. The sync detector 211 re-arranges the sync byte as a first byte and transfers the first byte to the buffer 221 in step 467. However, if the input byte is not a sync byte, the sync detector 211 transfers the bytes to a designated byte buffer of the buffer 221 one by one in step 463. After the byte data input as described above is transferred, the next byte buffer of the buffer 221 is connected such that the next byte can be transferred to the next byte position of the buffer 221 when the next byte is input in step 465. The above-described operation is repeatedly performed until the end time.
The conventional packet synchronization method repeatedly performs an operation for retrieving input byte data and re-arranging a buffer position of the buffer 221 when the input byte data is a sync byte. Accordingly, the conventional synchronization detection method must retrieve a sync signal from every packet of a TS signal in the demultiplexer 140 of the serial structure as illustrated in FIG. 3. That is, the sync detector 211 must retrieve the sync signal from every packet of the TS signal, detect the start of packet data after detecting the sync signal, and apply the remaining packet data to the buffer 221. However, a sync signal position of consecutive packet data can be detected once a sync signal of the packet data is detected because the TS signal is a conventional packet stream. Synchronization of packet data can be detected without retrieving a sync signal from every packet, but the conventional demultiplexer 140 repeatedly performs the operation for retrieving the sync signal from every packet.